The present invention relates to a novel process for preparing a gel polymer of vinyl compounds suitable for use as a coating, and, more particularly, relates to a process for the preparation of crosslinked polymers of water-soluble or water-dispersible vinyl compounds in the presence of specified catalysts. The present invention also relates to the gel polymer and the coating thereof.
The preparation of crosslinked polymers of vinyl monomers is well-known in the art. Known processes include:
(I) THE POLYMERIZATION PROCESSES USING A REDOX CATALYST;
(II) THE POLYMERIZATION PROCESSES USING A RADICAL CATALYST, AND;
(III) THE POLYMERIZATION PROCESSES USING AN ACTIVATION ENERGY SUCH AS ULTRAVIOLET RAY, ELECTRON BEAM, .gamma. RAY AND THE LIKE.
Of the above polymerization processes for polymerizing vinyl monomers, the processes (i) have been widely utilized as a process for graft-polymerizing vinyl monomers onto cellulose due to the fact that the polymerization can be performed at a relatively low temperature and even in the presence of air. However, in these processes, the rate of the polymerization reaction is generally extremely low. Contrary to the processes (i), although the processes (ii) and (iii) have been well-known as processes for polymerizing vinyl monomers at a high polymerization rate, in these processes, the presence of oxygen in the polymerization system inhibits the radical polymerization of vinyl monomers because the oxygen acts as a polymerization inhibitor, and the production of the desired polymer is difficult. Especially, when vinyl monomers are directly applied to the surface of a substate to be coated, polymerized and hardened in an atmosphere containing oxygen, such as in the air by using said processes (ii) or (iii) to thereby form a coating on the substrate, special conditions are necessary in order to prevent a phenomenon of stickiness of the surface of a coating due to the polymerization inhibition effect of oxygen.
The object of the present invention is to provide a process for polymerizing vinyl monomers even in the presence of oxygen at a high polymerization rate and without having a polymerization inhibition effect due to oxygen.
Another object of the present invention is to provide a gel polymer of vinyl compounds suitable for a coating on a substrate.
Other objects and advantages of the present invention will be apparent from the following description.